package com.gitee.feizns.explore.data_structure.linked_list.singly.merge;

/**
 * 合并两个有序链表
 * 将两个有序链表合并为一个新的有序链表并返回。新链表是通过拼接给定的两个链表的所有节点组成的。
 *
 * 示例：
 *
 * 输入：1->2->4, 1->3->4
 * 输出：1->1->2->3->4->4
 * @author feizns
 * @since 2019/10/9
 */
public class MergeList {

    public static void main(String[] args) {
        ListNode node = create1();
        node.print();
        ListNode node1 = create2();
        node1.print();
        mergeTwoLists2(node, node1).print();
    }

    public static ListNode mergeTwoLists(ListNode l1, ListNode l2) {
        if ( l1 == null )
            return l2;
        else if ( l2 == null )
            return l1;

        ListNode ret = l1.val > l2.val ? l2 : l1;
        ListNode curt = ret;
        ListNode ano = curt == l1 ? l2 : l1;
        while ( curt.next != null ) {
            ListNode next = curt.next;
            if ( next != null ) {
                if ( next.val <= ano.val ) {
                    curt = next;
                } else {
                    curt.next = ano;
                    curt = ano;
                    ano = next;
                }
            }
        }
        curt.next = ano;
        return ret;
    }

    private static ListNode create1() {
        ListNode node = new ListNode(1);
        node.next = new ListNode(2);
        node.next.next = new ListNode(3);
        return node;
    }

    private static ListNode create2() {
        ListNode node = new ListNode(5);
        node.next = new ListNode(7);
        node.next.next = new ListNode(9);
        return node;
    }

    public static ListNode mergeTwoLists2(ListNode l1, ListNode l2) {
        if ( l1 == null )
            return l2;
        else if ( l2 == null )
            return l1;

        if ( l1.val < l2.val ) {
            l1.next = mergeTwoLists(l1.next, l2);
            return l1;
        } else {
            l2.next = mergeTwoLists(l2.next, l1);
            return l2;
        }
    }

}
